This specification relates to generating query suggestions for presentation to users. Internet search engines provide information about Internet accessible resources (e.g., Web pages, images, text documents, and multimedia content) that are responsive to a user's search query by returning a set of search results in response to the query. A search result may include, for example, a Uniform Resource Locator (URL) and a snippet of information for resources responsive to a query.
Some Internet search engines provide query suggestions as a user is entering a query. These query suggestions generally correspond to possible completions of the user's input.
For example, if a user types “formic acid prop,” a search engine may suggest the query completion “formic acid properties.” These query suggestions can be presented, for example, in a drop down box that lists the query suggestions.